But not all of these lenders have been as generous as they seem. Despite the Government's bluster, and much to the anger of many borrowers, the gap between mortgage rates and the bank rate remains bigger than it has ever been in 13 years. Jeff Prestridge reports.

As the country's largest building society and now the only real rival to the big High Street banks, Nationwide likes to show that it looks after its customers - borrowers and savers alike.

So when the base rate came crashing down ten days ago, Nationwide was among the first to announce that its variable mortgage rate would be cut, along with HSBC and Lloyds TSB owned Cheltenham & Gloucester.

Though the 0.69 of a point reduction to its standard variable mortgage rate was not as generous as Gordon Brown would have wished, it means that Nationwide's SVR (or base mortgage rate, as Nationwide calls it) is now a respectable 4%.

So far the only other lender to have matched Nationwide's SVR in the wake of the base rate cut is Lloyds TSB, though HSBC-owned First Direct has cut rates even further - to 3.69%.

However, Nationwide isn't acting as altruistically as the Prime Minister and the outside world might be led to believe. This is because many Nationwide customers have home loans with the mutual's subsidiaries and they are paying much more in interest.

Like many building societies, Nationwide set up or bought a number of lending companies to target specific parts of the home loans market, such as buy-to-let or self-certified mortgages. The objective of these businesses, whose customers are not Nationwide members, is simple - o generate extra profit.

Nationwide's specialist lending arms are UCB Home Loans and The Mortgage Works, the latter acquired from Portman when it was taken over by Nationwide last year. The SVRs charged by these lenders are 5.29% and 5.19% respectively. From the start of next year, the rates will be trimmed by just 0.3 of a point, to 4.99% and 4.89% respectively.

Ray Boulger, mortgage expert at broker Charcol, says it is debatable whether the near-one percentage point premium that borrowers with these subsidiaries are paying above Nationwide's rate could be seen as reasonable.

'People who borrow through such specialist companies represent a higher risk for the lender, so it is not unusual for this risk to be priced into the mortgage rate,' he says. 'But a premium of one percentage point? It seems steep.'

Our mortgage has barely fallen

For Bob and Claire Harding, the base rate cuts from 5% to 2% have made little difference to their monthly mortgage payments - despite the fact that they have a variable-rate loan with Nottingham Building Society.

The mortgage payments on their four-bedroom detached house in Chelmsford, Essex, are principally based on Nottingham's standard variable rate.

But because Nottingham has only reduced its SVR from 7.24% to 6.49% since the first base rate cut in October, the Hardings' mortgage payments remain stubbornly high. From January their total monthly payments will be just £7 less than they were in November.

Claire, a 51-year-old human resources adviser for NHS trust South Essex Partnership, says: 'Gordon Brown has browbeaten some of the big lenders into reducing SVRs, but the small lenders seem to have fallen below his radar.'

Only five lenders have higher SVRs than Nottingham and they are all building societies. They are Chesham (6.7%), Kent Reliance (6.75%), Stroud & Swindon (6.79%), Bath (6.85%) and Scarborough (6.94%).

A recent survey by analysts at financial information group Moneyfacts found that such anomalies mean that the difference between average mortgage rates and the base rate is greater than it has been at any time in the past 13 years.

Nationwide refuses to disclose 'for commercial reasons' how many of its borrowers are on an SVR with these two companies, but it is not alone in applying higher SVRs to specialist lending arms.

About 12% of Yorkshire Building Society's mortgage book is on an SVR, but not all are paying its headline standard variable rate of 5.6%, which has yet to be adjusted for the recent one point cut in the base rate.

Customers of the mutual's Accord Mortgages business - providing loans through brokers only - are paying 5.99%.

Similarly, Britannia's SVR borrowers are paying 5.3%, while the rate at its specialist lending subsidiary Platform is 6. From the start of next year, the rate for Platform borrowers will fall to five% because it is set at three points above the base rate, but this will still be substantially higher than Britannia's own SVR if, as expected, that falls below 5%.

The two others of the top ten building societies that have specialist subsidiaries - Coventry and Skipton - do not discriminate against SVR customers who have borrowed through specialist subsidiaries.

Coventry has 9,000 borrowers on SVRs, including those with its Godiva subsidiary. As with Yorkshire's Accord, Godiva loans are available only through brokers and tend to be for buy-to-let purposes. However, the SVR is the same as for Coventry borrowers. Coventry's SVR is 5.34%, though it will come down in response to the latest base rate cut.

Coventry chief executive David Stewart says: 'We believe we should treat our mortgage customers the same, irrespective of whether they came to us through one of our branches or via a broker. It's a market position we feel comfortable with - it's clear, fair and transparent.'

Mortgage borrowers on an SVR with Skipton's subsidiary, Amber, are paying 6% compared with the 5.95% paid by Skipton's 20,000 SVR customers. However, from January both SVRs will drop to 5%.

The other top ten building societies do not have specialist lending subsidiaries. Of those that have already cut the SVR, the new rates are 4.99% at Newcastle and 5.79% at Chelsea. Those yet to trim rates include Leeds (whose SVR is 5.94%), Principality (5.99%) and West Bromwich building societies (5.84%).